A New Aglyptorhynchus (Perciformes: Scombroidei) From the Lincoln Creek Formation (Late Oligocene, Washington, U.S.A.)

Harry L. Fierstine, California Polytechnic State University - San Luis Obispo

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Copyright © 2005 Society of Vertebrate Paleontology. Journal webpage: http://vertpaleo.org/publications/JVPContent.cfm.

Abstract

A partial rostrum with an attachcd lower jaw, a posterior neurocranium, and a proximal hyomandibular from the Lincoln Creek Formation (late Oligocene, Washington) arc described and identified as Aglyptorhynchlls coillmhianlls sp, nov. In addition. ten articulated anterior caudal vertebrae presumably from the Lincoln Creek Formation arc described and identified as Aglyptorhyllchlls sp. This is a second record of an Aglyptorhynchus from a deposit bordering the Pacific Ocean, The specimens are compared with other billfishes (Perciformes: Scombroidei), both extant and extinct. Unusual features include a tripartite celous occipital condyle composed equally of the basioccipital and cxoccipitals, a lower jaw that is nearly twice as deep as the corresponding section of the rostrum, a subtemporal fossa, an oval-shaped fossa in the parasphenoid, two sphenotic ridges separated by a fossa, a bifurcated pterotic ridge. and a hyomandibular with a laterally curved posterior margin. With the exception of the deep lower jaw. these features have never been recorded before in extinct or extant scombroid fish, Heretofore. a tripartite occipital condyle was unknown in a non-beryciform percomorph fish, AglyplOrhynchlls is placed in the Scombroidei. family incertae sedis, because of the paucity of shared characters with other scombroid taxa.